Optimised cushioning in diabetic footwear can significantly enhance their capacity to reduce plantar pressure

Background: Plantar pressure reduction with the use of cushioning materials play an important role in the clinical management of the diabetic foot. Previous studies in people without diabetes have shown that appropriate selection of the stiffness of such materials can significantly enhance their capacity to reduce pressure. However the significance of optimised cushioning has not been yet assessed for people with diabetic foot syndrome. Research question: What is the potential benefit of using footwear with optimised cushioning, with regards to plantar pressure reduction, in people with diabetes and peripheral neuropathy? Methods: Plantar pressure distribution was measured during walking for fifteen people with diabetic foot syndrome in a cohort observational study. The participants were asked to walk in the same type of footwear that was fitted with 3D-printed footbeds. These footbeds were used to change the stiffness of the entire sole-complex of the shoe; from very soft to very stiff. The stiffness that achieved the highest pressure reduction relative to a no-footbed condition was identified as the patient-specific optimum one. Results: The use of the patient-specific optimum stiffness reduced, on average, peak pressure by 46% (±14%). Using the same stiffness across all participants lowered the footwears' capacity for pressure reduction by at least nine percentile points (37% ± 17%); a statistically significant difference (paired samples t-test, t(13) = −3.733, p = 0.003, d = 0.997). Pearson correlation analysis indicated that patient-specific optimum stiffness was significantly correlated with the participants’ body mass index (BMI), with stiffer materials needed for people with higher BMI (rs(14) = 0.609, p = 0.021). Significance: This study offers the first quantitative evidence in support of optimising cushioning in diabetic footwear as part of standard clinical practice. Further research is needed to develop a clinically applicable method to help professionals working with diabetic feet identify the optimum cushioning stiffness on a patient-specific basis.